420636021 has 16 divisors (see below), whose sum is σ = 612501120. Its totient is φ = 255205440.

The previous prime is 420636011. The next prime is 420636071. The reversal of 420636021 is 120636024.

It is not a de Polignac number, because 420636021 - 2⁵ = 420635989 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 420635982 and 420636000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (420636011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 73186 + ... + 78723.

It is an arithmetic number, because the mean of its divisors is an integer number (38281320).

Almost surely, 2^420636021 is an apocalyptic number.

It is an amenable number.

420636021 is a deficient number, since it is larger than the sum of its proper divisors (191865099).

420636021 is a wasteful number, since it uses less digits than its factorization.

420636021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151996.

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 420636021 is about 20509.4129852612. The cubic root of 420636021 is about 749.2650702952.

It can be divided in two parts, 42063 and 6021, that added together give a palindrome (48084).

The spelling of 420636021 in words is "four hundred twenty million, six hundred thirty-six thousand, twenty-one".